The present invention relates to a three-point safety belt system for motor vehicles with a belt point serving as the belt strap deflection or belt strap fastening at a side wall of a vehicle body and near an upper edge of a backrest of a vehicle seat assigned to the safety belt.
Conventional three-point safety belt systems have a deflecting and fastening point for the belt strap on the B-column of the vehicle body. To provide an optimal course of the belt strap, this belt point as a rule is higher than the window ledge of the vehicle body. By contrast, in vehicles without such a B-column (these are particularly vehicles with an open vehicle body, i.e., convertibles) the belt point may at most be arranged at the level of the window ledge.
For such a case, the German Patent Document DE-PS 27 27 125 provides a hump which is placed or formed onto the window ledge. The belt strap emerges at the highest point of the hump. Although, as a result of this measure, the course of the belt strap can be optimized, the visual appearance of the vehicle is impaired.
An object of the invention is to provide a mounting site for a belt point for a motor vehicle in which the mentioned belt point cannot be arranged on a B-column, which ensures optimal protection by means of the safety belt in event of a crash, but does not impair the appearance of the vehicle.
This and other objects are achieved by the present invention which provides a three-point safety belt system for motor vehicles with a belt point serving as at least one of a belt strap deflection and a belt strap fastening at a side wall of a vehicle body of the motor vehicle near an upper edge of a backrest of a vehicle seat assigned to the safety belt, wherein the belt system is configured such that the belt point is displaced upward when a given vehicle deceleration is exceeded.
According to the invention, the belt strap point can be displaced upward as soon as the vehicle is decelerated beyond a given value. As a result, it is achieved that in the normal case, the belt strap point is at most at the level of the window ledge and, because it is situated in the interior, is covered by the window ledge and thus is not visible from the outside. It therefore does not interfere with the lines and thus the appearance of the vehicle body.
By contrast, in the event of a crash, the belt point is displaced upward and provides a course of the belt strap which is optimal for the safety of the person wearing the safety belt.
The displacement of the belt point may be carried out in different manners. Thus, hydraulic and pneumatic control elements are suitable as well as electric control elements. When appropriate, pyrotechnical elements may also be used.
The unlocking for the displacement of the belt point may expediently be initiated by means of an existing air bag sensor. This is particularly advantageous when the displacement of the belt point takes place electromechanically or pyrotechnically.
In a particularly simple and expedient embodiment, a spring is used for the displacement of the belt strap.
Three-point safety belt systems are as a rule constructed so that the belt strap extends from a belt rewinder fastened in the lower area of the vehicle body side wall upwards to a deflection lug. There, it is deflected and extends transversely over the shoulder of the vehicle occupant to a lock tongue which is inserted into a belt buckle fastened in the area of the cardan tunnel or at the seat or the seat rail. From the lock tongue, the belt strap extends via the pelvis of the vehicle occupant back to the exterior side and is fastened there in the proximity of the vehicle body floor or on the seat or the seat rail.
In an advantageous embodiment, with such a course of the belt strap, the belt point is a deflection lug which deflects the belt strap in the direction of the upper part of the body of the vehicle occupant. In this case, the deflection lug is connected with a sliding block which is perpendicularly movable in a guide fixed to the vehicle body. By means of these devices, the displaceability of the deflection point is ensured in a simple manner.
If the displacement is to take place by means of spring force, a compression spring is provided between the sliding block and a support fixed to the vehicle body. The compression spring will be compressed and thus prestressed as soon as the belt point moves into its lower and therefore into its normal position or is situated there. A locking mechanism, which in an expedient manner responds to the vehicle deceleration, holds the spring in the prestressed condition.